A structure having the semiconductor element, the pair of metallic electrodes and the insulating substrate is formerly proposed as the semiconductor device in U.S. Pat. No. 6,072,240. The metallic electrode is arranged so as to nip (i.e., sandwich) the semiconductor element, and functions as an electrode of the semiconductor element and a heat radiating member. The insulating substrate is arranged on a face on a side opposed to a nipping face of the semiconductor element in each metallic electrode and has a heat radiating property and is manufactured by ceramic.
In this structure, the semiconductor element is formed in a shape arranged so as to be nipped by both the metallic electrodes on opposite faces of both the opposed metallic electrodes, i.e., on an inner face side. The semiconductor element can take out an electric signal by the metallic electrode from both faces of the semiconductor element.
Further, an outer face of each metallic electrode is brazed to the insulating substrate, and a cooling device is attached to the outer face side of each insulating substrate so that heat can be radiated from the semiconductor element from its both faces. Here, an electric insulating property of the metallic electrode and the cooling device is secured by the insulating substrate manufactured by ceramic.
However, the former semiconductor device causes the problem that the insulating substrate is warped by a temperature cycle change, etc. due to a difference in coefficient of thermal expansion between the insulating substrate constructed by ceramic and the metallic electrode constructed by a metal.
For example, when the warp of the insulating substrate is large, problems are caused in that a close attaching property of the cooling device and the insulating substrate becomes insufficient, and an assembly property in nipping the semiconductor device by the cooling device is obstructed by deterioration of a parallel degree between both the insulating substrates, etc.